Do you mean that you want to pass the object to some classes as reference !?
Possible after PHP 5.3 (i think)
(good explanation not in french... even if they've fr in the link and a lot more on the page)
Basically, you can pass a reference on the object to any of your classes.
And they'll all manipulate the same values in memory !
It save memory and operation of duplications.
If I've not understant the question... sorry in advance